Various methods have been proposed for protecting goods and documents from counterfeit protection. Some such methods include creating images which may be embedded and/or concealed as encoded, hidden images. The images cannot easily be seen, if at all, without the use of a special device to decode, or reveal, an authentication image when placed over the location of the encoded image. When a decoder is placed over a branded good, for example, at a location where an authentic product is known to contain an encoded image, a party may be able to verify the good's authenticity by whether or not the authentication image is revealed when one views the location through the decoder.
In many cases, a party interested in investigating whether not a product or document is authentic may be conducting the investigation in a low light situation, such as a warehouse or shipyard where goods are often subject to inspection. Similarly, a police officer may want to determine the authenticity of a driver's license during a night time traffic stop along a dimly lit street. These low light situations can make authentication difficult.